Masuma, pronounced as (MU)st + (SOO)n + (MU)st, is an Arabic name that means innocent, protected, free from sins. It is the nickname of Fatima, daughter of Musa al-Kadhim, the 7th Shiite Imam. For this reason it is a common name among the Shiite, but not among Sunni/Mainstream Muslims. It is an indirect Quranic word. If you are Sunni I suggest that you do not use this name due to the Shiite connotations which could confuse many people into thinking that your child comes from a Shiite family.